1zsc000498-abh en, rev. 1 motor-drive mechanisms ... en, rev. 1 | maintenance guide bue/bul2 7 1....

Motor-drive mechanisms, types BUE and BUL2Maintenance guide

1ZSC000498-ABH en, Rev. 1

Original instruction

The information provided in this document is intended to be general and does not cover all possible applications. Any specific application not covered should be referred directly to ABB or its authorized representative.

ABB makes no warranty or representation and assumes no liability for the accuracy of the information in this document or for the use of such information. All information in this document is subject to change without notice.

This document must not be copied without our written permission, and the contents thereof must not be imparted to a third party nor be used for any unauthorized purpose. Contravention will be prosecuted.

Recommended practicesABB recommends careful consideration of the following factors when installing on-load tap-changers:

Before you install or commission a unit, make sure that the personnel doing the job have read and fully understood the Installation and commissioning guide provided with the unit.

To avoid damaging the unit, never exceed the operating limits stated in delivery documents and on rating plates.

Do not alter or modify a unit without first consulting ABB.

Follow local and international wiring regulations at all times.

Use only factory-authorized replacement parts and procedures.

WARNING, CAUTION and INFO

WARNING

WARNING indicates an imminently hazardous situation which if not avoided, will result in death or serious injury. This signal word is to be limited to the most extreme situations.

WARNING also indicates a potentially hazardous situation which if not avoided, could result in death or serious injury.

CAUTION

CAUTION indicates a potentially hazardous situation which if not avoided, may result in minor or moderate injury. It may also be used to alert against unsafe practices.

CAUTION may also indicate property-damage-only hazards.

INFO provides additional information to assist in carrying out the work described and to provide trouble-free operation.

Safety precautions

WARNING

The maintenance guide should be read and understood before any work is started, and the procedures in the document should be followed at all times.

WARNING

Before starting any work inside the motor-drive mechanism, the auxiliary power must be switched off. N.B. The motor, the contactors and the heating element may be energized from separate sources.

During service

WARNING

Small amounts of explosive gas might come out from the breathing devices (dehydrating breather or one-way breather). Make sure that no open fire, hot surfaces or sparks occur in the immediate surroundings of the breathing devices.

WARNING

If a failure in power supply occurs during operation, the operation will be completed when the power returns.

WARNING

The hand crank must not be inserted during electrical operation.

WARNING

If the tap-changer is not in its exact position and the hand crank is pulled out, the motor-drive mechanism will start and run to the exact position if the power supply is on.

Content1. Introduction ..........................................................................................................................7

1.1 General ........................................................................................................................71.2 Design ..........................................................................................................................71.3 Legend .........................................................................................................................7

2. Inspection .............................................................................................................................122.1 Required tools and material ..........................................................................................122.2 Procedure .....................................................................................................................12

3. Overhaul ...............................................................................................................................133.1 Required tools and materials .........................................................................................133.2 Motor protection ...........................................................................................................133.3 Ground fault protector (option) ......................................................................................133.4 Counter ........................................................................................................................133.5 Heater ...........................................................................................................................133.6 Toothed belt ..................................................................................................................143.7 Motor cable connections ..............................................................................................143.8 Overhaul type BUE .......................................................................................................14

3.8.1 Disc brake ..............................................................................................................143.8.2 Brake for the holding contact ..................................................................................153.8.3 Position transmitter and other position switches .....................................................153.8.4 Lubrication .............................................................................................................15

3.9 Overhaul type BUL2 ......................................................................................................173.9.1 Disc brake ..............................................................................................................173.9.2 Position the transmitter and other position switches ...............................................173.9.3 Lubrication .............................................................................................................17

3.10 Operation test .............................................................................................................18

4. Specification of materials ......................................................................................................19

1ZSC000498-ABH en, Rev. 1 | Maintenance guide BUE/BUL2 7

1. Introduction

1.1 General The motor-drive mechanisms, types BUE and BUL2, manufactured by ABB, have been developed over many years to provide maximum reliability. The simple and robust design gives a service life equal to the service life of the transformer. Minimum maintenance is required for trouble-free operations.

The motor-drive mechanism is attached to the transformer tank and connected to the on-load tap-changer by means of drive shafts and a bevel gear.

1.2 DesignThe design and layout of the motor-drive mechanisms are shown in Figs. 1 and 2 (BUE) and Figs. 3 and 4 (BUL2).

1.3 Legend

Towards motor-drive upper limit

Towards motor-drive lower limit

LOCAL control

REMOTE control

8 Maintenance guide BUE/BUL2 | 1ZSC000498-ABH en, Rev. 1

101 4 568 83 2 97 11

12

15

14 13 16

1. Locking device prepared for padlock2. Emergency stop3. Air vent4. LOCAL/REMOTE switch 5. RAISE/LOWER switch6. Outgoing shaft7. Lamp (40 W socket E27)8. Lifting eye9. Counter

10. Tap-change in progress indicator11. Position indicator with drag hands for max. and min.

position12. Shaft for hand crank13. Protective motor switch14. Door-operated switch for lamp15. Hand crank16. Descriptions and circuit diagram

Fig. 1. Cabinet layout of motor-drive mechanism, type BUE.


Fig. 2. Mechanical design of motor-drive mechanism, type BUE.

Position transmitter

Contact plate

Brake

Roll pin

Supporting shaft

Holding contact

Brake disc

Brake block

Brake for holding contact

Cam disc

Motor

Toothed belt

Arm system

Drive roller

One turn shaft

Geneva wheel


1

12

7

8

9

11

13

6

15

6

16

10

2 14 34 5

1. Position indicator with drag hands for max. and min. position

2. Tap-change in progress indicator (Red: in progress, White: in position)

3. Counter4. Outgoing shaft with multi-hole coupling half5. Shaft for hand crank6. Locking device prepared for padlock7. (Option) Outlet

8. Emergency stop9. RAISE/LOWER switch10. LOCAL/REMOTE switch 11. Protective motor switch12. Air vent13. Door-operated switch for lamp14. Lamp15. Descriptions and circuit diagram 16. Hand crank

Fig. 3. Cabinet layout of motor-drive mechanism, type BUL2.


Operation counter

Roller

Notch

Cam disc

Brake arm

Geneva wheel

(Grease)

(Grease)

Adjusting screw

Holding contact

Brake disc

Multi-position switches

Limit switch

Bracket

Toothed belt

(Grease)

Fig. 4. Mechanical design of motor-drive mechanism, type BUL2.

(Grease)


The inspection mainly consists of a visual check of the motor-drive mechanism once a year while the transformer is in service. It is recommended to perform the inspection of the motor-drive mechanism and the other parts of the tap-changer at the same time. See the respective maintenance guide.

In the motor-drive mechanism, the following points are to be checked:

– Motor and counter – Heater – The counter’s value – Visual check of toothed belt

2.1 Required tools and materialThe following equipment is required for the inspection:

– Set of screw drivers

2.2 Procedure

WARNING

This work must be carried out from ground level since the transformer is energized!

WARNING

Before starting any work inside the motor-drive mechanism, the auxiliary power must be switched off. N. B. The motor, contactors and heating element may be energized from separate sources.

1. Open the cabinet door of the motor-drive mechanism and turn the selector switch to the LOCAL position. Then turn the control switch to the RAISE (LOWER) position.

2. Inspection

2. Check that the motor works properly, the position indicator increases (decreases) one step and the counter advances one step for each operation. Record the counter’s value. The counter shows the number of operations run by the tap-changer (the overhaul schedule can be determined with the help of this information).

3. Turn the control switch to the LOWER (RAISE) position for 1-2 seconds. Check that the motor also works properly in that direction, the position indicator decreases (increases) one step and the counter advances one more step. Reset the drag hands.

4. Check the emergency stop. Trigger a RAISE or LOWER impulse and after about one second, press the emergency stop. The operation should be interrupted. Reset the emergency stop by turning the knob clockwise and by switching on the protective motor switch. The started operation should now be completed. Operate back to the service position.

5. Check the ground fault protector (option). If the motor-drive mechanism is equipped with an outlet, the ground fault protector should be tested by pressing the test knob on the outlet.

6. Disconnect the incoming auxiliary power.

7. Open the control panel.

8. Check by feeling with a finger that the elements have been functioning.

9. Close the control panel and reconnect the incoming auxiliary power.

10. Complete the inspection by turning the switch to the REMOTE position and closing the cabinet door.


WARNING

Before any work is carried out on the tap-changer: Make sure that the transformer is disconnected and that grounding is properly carried out. Obtain a signed certificate from the engineer in charge.

3.1 Required tools and materialsNecessary for the overhaul is the following equipment:

– Normal hand tools (wrench sizes up to 19 mm) – Standard set of combination wrenches – Sliding caliper – Spring balance (10 N) – Grease (GULF-718 EP synthetic grease, Mobilgrease 28,

Shell-Aero Shell grease 22 or similar – Oil (for plain ball and roller bearings)

The motor-drive mechanism should normally be regularly overhauled at intervals of 300,000 operations. The number of operations must not exceed 1,500,000, which is the mechanical lifetime of the motor-drive mechanism.

It is recommended to perform the overhaul of the motor-drive mechanism and the other parts of the tap-changer at the same time. See the appropriate maintenance guide for the tap-changer.

The overhaul includes the following points:

Before disconnecting the power supply: – Motor protection function (Section 3.2) – Ground fault protector (option) (Section 3.3) – Counter function (Section 3.4)

After disconnecting the power supply: – Heater function (Section 3.5) – Toothed belt (Section 3.6) – Cable connections (Section 3.7) – Disc brake function (Section 3.8.1 for BUE; Section 3.9.1

for BUL2) – Position transmitter and other position switches

(Section 3.8.3 for BUE; Section 3.9.2 for BUL2) – Lubrication (Section 3.8.4 for BUE; Section 3.9.3 for BUL2)

Reconnect the power supply and carry out operation tests according to the instructions in the tap-changer installation guide.

3. Overhaul

3.2 Motor protection

WARNING

The motor power voltage is dangerous.

The function of the protective motor switch is checked. For three-phase AC motors, one of the phase fuses is removed and the function time of the protective motor switch is checked by a RAISE or LOWER operation. The protective motor switch shall release within 60 seconds at a current setting equal to the rated current of the motor at actual voltage.

If the protective motor switch does not trip within 60 seconds, switch off the power and adjust the current setting. Repeat the test when the motor is cold.

Protective motor switches for DC motors and for single-phase AC motors are not tested.

3.3 Ground fault protector (option)If the motor-drive mechanism is equipped with an outlet, the ground fault protector should be tested by pressing the test knob on the outlet.

3.4 CounterCheck that the counter is functioning for RAISE and LOWER operations.

Check that the position indicator increases (decreases) one step and the counter advances one step for each operation. Record the counter's value. The counter shows the number of operations run by the tap-changer.

3.5 Heater

WARNING

Before starting any work inside the motor-drive mechanism, the auxiliary power must be switched off. N. B. The motor, contactors and heating element may be energized from separate sources.

Check by feeling with a finger that the elements have been functioning.


3.6 Toothed beltCheck that the toothed belt is sufficiently tight. If tightening is required, adjust the motor support. The tightness of the belt can be checked by a spring balance attached to the belt halfway between the pulleys (see Fig. 5). At a 10 N load the belt should yield about 5 mm on BUE, and at a 6 N load the belt should yield about 2 mm on BUL2.

3.7 Motor cable connectionsCheck that all cable connections within reach are secure.

3.8 Overhaul type BUE3.8.1 Disc brakeWipe the brake disc free from grease.

See Fig. 6. The kinetic energy in the motor and the toothed wheels should be absorbed by the brake, and the motor-drive mechanism should stop with a tolerance of ± 25° as measured on the brake disc (± 125° measured on the hand crank).

This can be adjusted by tightening both of the spring bolts on the brake. Using the hand crank, operate the motor-drive mechanism until the brake is fully open. At this point the length of the springs must not be less than 35 mm. If the brake still does not function with that spring length, oil or grease has entered the brake linings, which will then need cleaning.

Clean as follows: Using a pair of tongs, remove the roll pins that hold the supporting shafts on the brake blocks; see Fig. 2. Then remove the shaft and the brake blocks. Clean the brake linings on the two brake blocks with degreasing agent.

When refitting the brake, check that the brake disc is completely free from grease. Adjust the spring force of the brake until the motor-drive mechanism stops within the tolerances given above.

Red mark ±25° from mark on brake pad

Brake disc

Red mark

Brake pads

Adjusting nuts

Fig. 6. Brake adjustment, type BUE.

Fig. 5. Check of toothed belt.

Apply load

Yield


CAUTION

If the motor-drive still does not stop when the brake is adjusted to a spring length of 35 mm when the brake is fully open, please contact ABB for advice.

3.8.2 Brake for the holding contactCheck that the brake for the holding contact prevents the arm system on the holding contact shaft from swinging beyond its normal position when the roller on the drive arm moves free from the cam disc; see Fig. 2. At the end of the operation, contacts for operation in the opposite direction should not move when the arm system swings back towards its normal position.

Unpermitted swinging should be prevented by raising the braking force, i. e. tightening the spring bolt.

An adjusted, increased spring force on the brake makes the holding contact arm swing back with a different speed, and the brake for the holding contact must be adjusted.

0.8 mm+0.3 -0.3

Contact arm

View A – A

Moving contact

Fixed contactContact plate

Contact arm

Geneva wheel

Fig. 7. Contact arm play.

3.8.3 Position transmitter and other position switchesClean the contact plates and arms (Fig. 7) from dust and dirt with a dry cloth.

Check and adjust the resilience of the moving contacts in the multi-position switches. The moving contact shall in all positions, have a clearance between the nut and the contact arm of 0.5–1.1 mm. Adjustment is made with the nuts on the contact.

3.8.4 LubricationSee Fig. 8. The bearing points of the brake blocks and the links should be sparingly lubricated with oil. (Use oil for plain ball and roller bearings.)

The spur gears, the Geneva wheel with the limit-stop, the cam discs, the cam bar and the big wheel attached on the outgoing shaft, are sparingly lubricated with the same type of grease as for the shaft system when necessary.

Other bearing points do not need lubrication.

Protect the brake disc and the brake linings against lubricants. Wipe off excess lubricant.

Reconnect the power supplies.


NOTE: The small bevel gear for the position indicator shaft must be greased.

Fig. 8. Lubrication points, type BUE.

GreaseGrease

Oil

Grease

Grease

Grease

Oil


3.9 Overhaul type BUL23.9.1 Disc brakeRun the motor-drive mechanism and check that the center of the notch in the cam disc stops within ±2 mm from the center of the roller on the brake arm, see Fig. 9. If it does not stop within the tolerances, adjust the braking force with the adjusting screw at the lower end of the brake arm. Loosen the contra nut. Tightening the screw (clockwise) makes the stop occur earlier and loosening the screw (counterclockwise) makes the stop occur later. Tighten the contra nut after the adjustment.

CAUTION

If the motor-drive still does not stop when the brake is adjusted to min. 15 mm according to Fig. 9, please contact ABB for advice.

3.9.2 Position the transmitter and other position switchesCheck the contact function in all positions for both RAISE and LOWER operations.

No adjustment of the contacts should be made.

If there is excessive dust, it can be removed from the circuit boards and the transparent covers with a vacuum cleaner without disassembling the multi-position switch.

3.9.3 LubricationLubrication is not needed under normal operating conditions. All ball bearings have rubber seals and are permanently lubricated. All cam discs and some gears are made of self-lubricating material.

If needed, the gear for the outgoing shaft, the bevel gears for the hand crank, the Geneva wheels and the bevel gears for the position indicator can be sparingly lubricated with the same grease as for the shaft system. (GULF-718EP Synthetic Grease, Mobilgrease 28, Shell-Aero Shell Grease 22 or similar). See Fig. 4.

Reconnect the power supplies.

Roller on the brake arm in center of the notch in the cam disc

Cam disc

Contra nut

Brake arm

Adjusting screw

Min. 15

Fig. 9. Brake adjustment, type BUL2.

Brake disc

Fig. 10. Check of position transmitter.

Transparent cover

Circuit board

Contact arm


3.10 Operation testOperate the motor-drive mechanism, first with manual operation and then electrically between the limit-positions. Check the limit-stops by operating the tap-changer to one of the end-positions. When trying to operate it electrically beyond the end-position, the motor should not start. Check the mechanical end-stop by trying to hand crank it beyond the end-position. After a couple of turns on the hand crank, it should be mechanically stopped. Hand crank back to the end-position (where the indicator flag is positioned in the middle for the BUE, and when the indicator flag shows white color for the BUL2). Operate the tap-changer electrically to the other end-position and carry out the same test procedure as above.

Check the emergency stop by triggering a RAISE or LOWER impulse and after about one second, press the emergency stop. The operation should be interrupted. Reset the emergency stop by turning the knob clockwise and switch on the protective motor switch. The started operation should now be completed.

Check the run-through protection with the step-by-step function disengaged. This is done by first removing the connection between terminals X4:1 and X4:2 and then keeping the RAISE/LOWER switch engaged. The motor-drive mechanism should stop before the fourth operation is completed. This check must be performed at least five steps from the end-position. After the test, reset the time relay by setting the LOCAL/REMOTE switch to 0 and then back. Reset the protective motor switch to ON. Reconnect the connection between X4:1 and X4:2.

Check the step-by-step relay by keeping the RAISE/LOWER switch engaged in RAISE. The tap-changer shall advance only one step. Repeat the check for LOWER.

Check the function of the position transmitter and other multi-position switches in all positions.


4. Specification of materials

Material BUE

Approx.

amount

BUL

Approx.

amount

BUL2

Approx.

amount

Steel 100–120 kg 55 kg 25 kg

Aluminium and alloys – 10 kg 5 kg

Copper and alloys 5–10 kg 5 kg 65 kg

Silver 10 g 10 g x

Plastics:

chlorsulphonated

polyethylene

x x x

polyamide with MoS2 x x

phenol resin laminate x

polyester x x x

PVC x x x

carbonate plastic x x x

Rubbers:

nitrile rubber x x x

fluorine rubber x x x

CAUTION

Materials listed in the table above without any specification of amount are included because they may cause pollution problems during de-commissioning, even in the small quantities used.

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5ABB AB ComponentsSE-771 80 Ludvika, Sweden Phone: +46 240 78 20 00 Fax: +46 240 121 57 E-Mail: [email protected] www.abb.com/electricalcomponents

1zsc000498-abh en, rev. 1 motor-drive mechanisms ... en, rev. 1 | maintenance guide bue/bul2 7 1....

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